Iron in the Hallervorden-Spatz syndrome

The dark discoloration of globus pallidus and substantia nigra pars reticularis in the Hallervorden-Spatz syndrome is due to the accumulation of iron. Routine iron stains detect the metal mostly in microglia and macrophages, but scattered neurons are also reactive. Axonal spheroids are characteristic of the disease, and many of these expansions give a positive iron reaction. Globus pallidus and substantia nigra are normally rich in iron, and additional "storage" of the metal has often been considered the essential factor in the pathogenesis of Hallervorden-Spatz syndrome. However, other equally iron-rich structures, such as the red nucleus and the dentate nucleus, remain unaffected. In normal globus pallidus and substantia nigra pars reticularis, double-label immunofluorescence microscopy of ferritin, as an indirect marker of cellular iron localization, and phosphorylated neurofilament protein reveal close proximity of ferritin-reactive microglial and oligodendroglial processes to tightly packed axons. It is proposed that a primary axonal disorder allows the seepage of iron into the axoplasm. Iron may contribute to the axonal disease, but accumulation of the metal probably should be viewed as an epiphenomenon. Pallidal and nigral iron excess is not unique to Hallervorden-Spatz syndrome, and some previously reported postmortem examinations may actually represent pallidonigroluysian atrophy.

Genetic localization of an autosomal dominant leukodystrophy mimicking chronic progressive multiple sclerosis to chromosome 5q31

The hereditary leukodystrophies represent a group of neurological disorders, in which complete or partial dysmyelination occurs in either the central nervous system (CNS) and/or the peripheral nervous system. Adult-onset autosomal dominant leukodystrophy (ADLD) is a slowly progressive, neurological disorder characterized by symmetrical widespread myelin loss in the CNS, and the phenotype is similar to that of chronic progressive multiple sclerosis. We report clinical, neuroradiological and neuropathological data from the originally reported ADLD family. Furthermore, we have localized the gene that causes ADLD to a 4 cM region on chromosome 5q31. Linkage analysis of this family yielded a LOD score of 5.72 at theta = 0.0 with the microsatellite marker D5S804. Genetic localization will lead to cloning and characterization of the ADLD gene and may yield new insights into myelin biology and demyelinating diseases.

Oculoleptomeningeal amyloidosis associated with a new transthyretin variant Ser64

BACKGROUND

A Canadian family with oculoleptomeningeal amyloidosis with both central and peripheral nervous system disorders was described in 1988. Death of affected family members resulted from recurrent cerebral hemorrhage.

OBJECTIVE

To determine if oculoleptomeningeal amyloidosis is caused by a mutation in transthyretin (prealbumin).

METHODS

DNA isolated from peripheral blood and archival tissues of affected members of the kindred was studied by direct DNA sequencing and restriction fragment length polymorphism analysis.

RESULTS

Direct DNA sequencing identified a thymine-to-cytosine transition at the second base of codon 64, which resulted in a replacement of serine for phenylalanine. This mutation, which creates an additional HinfI site was detected by restriction fragment length polymorphism analysis in each affected individual.

CONCLUSION

In this kindred, oculoleptomeningeal amyloidosis is related to a mutation in transthyretin (Phe64Ser).

Synapses in the hereditary ataxias

The goal of this investigation was the systematic assessment of synapses in the hereditary ataxias by the immunocytochemical and immunofluorescent visualization of SNAP-25, a protein of the presynaptic membrane. Sections were prepared from the cerebellar cortex, dentate nucleus, basis pontis, inferior olivary nuclei, and the spinal cord in 57 cases of autosomal dominant and recessive ataxia. The neuropathological phenotype included 18 cases of olivopontocerebellar atrophy (OPCA), 14 cases of familial cortical cerebellar atrophy (FCCA), 4 cases of Machado-Joseph disease (MJD), and 21 cases of Friedreich's ataxia (FA). Among the autosomal dominant ataxias, spinocerebellar ataxia type 1 (SCA-1), SCA-2, MJD/SCA-3, and SCA-6 were represented. Expanded guanine-adenine-adenine trinucleotide repeats were confirmed in 7 patients with FA. The abundance of SNAP-25 was estimated by comparing the fluorescence of the regions of interest to that of the frontal cortex, which was considered unaffected by the disease process. Despite severe Purkinje cell loss, abundant SNAP-25 reaction product remained in the molecular layer of FCCA and OPCA. Among the cases of OPCA, those identified as SCA-2 showed the most severe overall synaptic destruction in cerebellum and brain stem. In SCA-1, which caused either OPCA or FCCA, significant synaptic loss was restricted to the inferior olivary nuclei. Sparing of cerebellar cortex and inferior olivary nuclei was the rule for MJD/SCA-3 and FA, though the dentate nucleus showed reduced SNAP-25 immunoreactivity in both ataxias. In FA, preservation of SNAP-25 in the dentate nucleus was characteristic of long survival. Severe cases with short survival revealed synaptic depletion of the dentate nucleus. At the level of the spinal cord, synaptic loss in the dorsal nuclei of Clarke characterized FA and MJD/SCA-3. The inexorable clinical progression of the hereditary ataxias could not be attributed to synaptic loss in a single anatomic structure of cerebellum, brain stem, or spinal cord. Nevertheless, synaptic loss in dentate and inferior olivary nuclei correlated more precisely with the severity of the ataxia than the changes in the cerebellar cortex.

The hereditary ataxias

Efforts to classify the hereditary ataxias by their clinical and neuropathological phenotypes are troubled by excessive heterogeneity. Linkage analysis opened the door to a new approach with the methods of molecular biology. The classic form of autosomal recessive ataxia, Friedreich's ataxia (FA), is now known to be due to an intronic expansion of a guanine-adenine-adenine (GAA)-trinucleotide repeat. The autosomal dominant ataxias such as olivopontocerebellar atrophy (OPCA), familial cortical cerebellar atrophy (FCCA), and Machado-Joseph disease (MJD) have been renamed the spinocerebellar ataxias (SCA). Specific gene loci are indicated as SCA-1, SCA-2, SCA-3, SCA-4, SCA-5, SCA-6, and SCA-7. In 5 of them (SCA-1, SCA-2, SCA-3, SCA-6, and SCA-7), expanded cytosine-adenine-guanine (CAG)-trinucleotide repeats and their abnormal gene products cause the ataxic condition. The most common underlying loci for olivopontocerebellar atrophy (OPCA) are SCA-1 and SCA-2, although other genotypes may be added in the future. A major recent advance was the identification of the gene for SCA-3 and MJD, and the high prevalence of this form of autosomal dominant ataxia. In FA and the SCA with expanded CAG-trinucleotide repeats, clinical and neuropathological severity are inversely correlated with the lengths of the repeats. Anticipation in the dominant ataxias can now be explained by lengthening of the repeats in successive generations. Progress is being made in the understanding of the pathogenesis of FA and SCA as the absent or mutated gene products are studied by immunocytochemistry in human and transgenic murine brain tissue. In FA, frataxin is diminished or absent, and an excess of mitochondrial iron may cause the illness of the nervous system and the heart. In SCA-3, abnormal ataxin-3 is aggregated in neuronal nuclei, and in SCA-6, a mutated alpha1A-calcium channel protein is the likely cause of abnormal calcium channel function in Purkinje cells and in the death of these neurons.

Somatic mosaicism in the central nervous system in spinocerebellar ataxia type 1 and Machado-Joseph disease

Spinocerebellar ataxia type 1 and Machado-Joseph disease are two autosomal dominant cerebellar ataxias caused by expansions of unstable CAG repeats in the coding region of the causative genes. The selectivity of cell death and the resulting characteristic neuropathological features in each of these diseases are not explained by the gene expression patterns. Since the repeat size correlates with age at onset and severity of these diseases, somatic mosaicism, the result of mitotic instability of the CAG repeat, could be the basis for specificity of neurodegeneration; brain structures with larger expanded repeats would be more severely affected. To study the association between neuropathological changes and somatic mosaicism of the CAG repeat size in the central nervous system of patients with these two ataxias, we determined the size of the (CAG)n expansion in 20 different regions of the brain, brainstem, cerebellum, and spinal cord from 3 patients with spinocerebellar ataxia type 1 and 3 with Machado-Joseph disease; these regions were selected for their differential neuropathological involvement in the two disorders. We observed a considerable homogeneity of repeat size ranges in all but 1 of the 20 regions examined: The cerebellar cortex showed slightly smaller (CAG)n tracts in all specimens from both groups of patients. Our results suggest that the pattern of repeat size mosaicism, similar in spinocerebellar ataxia type 1 and Machado-Joseph disease, reflects the developmental pathways and cell composition of different central nervous system regions and is not the cause of selective cell death in these disorders.

The cellular reactions to experimental intracerebral hemorrhage

The resolution of an intracerebral hemorrhage can be measured by the occurrence of hemosiderin. Extravasation of blood elicits a cellular reaction in the adjacent surviving tissue where the lesion activates resident microglia and attracts many more phagocytes from the blood stream. The signals for this migration into the perifocal reactive zone are not fully understood but it is likely that proteins in the coagulated blood contribute to cellular activation. In order to study the role of plasma proteins in the pathogenesis of the perifocal reactive zone, intracerebral injections of either autologous whole blood (0.1 ml) or an equal volume of washed autologous red blood cells (RBC) in lactated Ringer's solution were made in adult rabbits. The amount of total iron was the same (30 micrograms). The cellular responses to the injections were studied by iron histochemistry and immunocytochemistry for ferritin, the ferritin repressor protein (FRP), the glial fibrillary acidic protein (GFAP), and the complement receptor CR3. Experimental hematomas resolved much more slowly after the injection of whole blood than after the injection of RBC. Qualitative microglial and astrocytic responses were quite similar. However, at 48 h, iron- and ferritin-reactive microglia were more numerous following the injection of whole blood. After injections of either type, ferritin-immunoreactive cells were more abundant than iron-positive cells. This observation implied that the biosynthesis of holoferritin protein and iron incorporation proceeded independently. Expression of CR3 on the surface of microglia was much more prominent after whole blood, suggesting a role of inactivated complement 3b in the attraction of additional phagocytes. Conversion to hemosiderin began at 5 days after the injection of either blood or RBC. The lesions caused initial destruction of astrocytes in the perifocal zone as judged by GFAP- and FRP-immunoreactivity. However, at 5 days, astrocytic processes reentered the perifocal zone and intermingled with microglia and macrophages. It is proposed that this contact between astrocytes and microglia reversed the uncoupling of ferritin biosynthesis and iron incorporation and initiated the storage of iron and formation of hemosiderin.

The history of iron in the brain

Brain iron research began in the late nineteenth century when Zaleski (1886) made a quantitative analysis of one human brain and correlated iron levels with observations on stained slices and some microscopic sections. Gradually, the realization grew that the central nervous system (CNS) contained iron which was different from hemoglobin-iron. This non-heme iron was found in highest concentrations in globus pallidus, substantia nigra, red nucleus, and dentate nucleus. The enhancement of the traditional histochemical stain, potassium ferrocyanide in hydrochloric acid, by incubating the reacted sections in a solution of diaminobenzidine and hydrogen peroxide, revealed iron in many cell types of the CNS, including neurons, microglia, oligodendroglia, and some astrocytes. A large proportion of the soluble brain iron was shown to be present in ferritin. Brain ferritin was found to be very similar to the protein from other organs in that it contained heavy and light subunits. Several investigators reported the presence of other iron-related proteins in the central nervous system, including transferrin, transferrin receptor, and the ferritin repressor protein. Brain was shown to respond to the extravasation of blood by converting the iron in heme to hemosiderin by a sequence of steps which was quite similar to the process in extracerebral organs. The methods of molecular biology have contributed greatly to our understanding of brain iron but many questions remain about its unique anatomical distribution and its role in degenerative diseases such as Parkinson's disease and Alzheimer's dementia.

The heterogeneous distribution of brain transferrin

Immunocytochemistry with antisera to transferrin has often been used to identify oligodendroglia in tissue sections and cultures, but reaction product also occurs in blood vessel walls and nerve cells. There is considerable species variation. Serum transferrin is largely biosynthesized in the liver, and its established physiological role is the transport of iron to tissue sites and delivery of the metal to the interior of cells that have transferrin receptors on their surfaces. In sections of the central nervous system, the visualization of iron and transferrin generally does not coincide, and transferrin may have importance to normal brain function beyond iron transport. For a comparative analysis of transferrin in rabbit and rat brain, polyclonal antisera were raised against purified serum transferrins of these species. The antisera were used for transferrin immunocytochemistry on vibratome sections and for immunochemical detection on electroblots. Transferrin immunocytochemistry and iron histochemistry were compared. The electrophoretic separation of brain extracts and transfer to nitrocellulose membranes permitted the quantitation of the protein and the study of the carbohydrate chains of tissue-bound transferrins by biotinylated lectins. An unexpected result in the rabbit was the dense immunocytochemical reaction product in Bergmann glia and Golgi epithelial cells. Reaction in the cytoplasm of oligodendrocytes was relatively faint in this species except for some selected white matter tracts, e.g. the inferior cerebellar peduncles. In sections of rat brain, oligodendrocytes and vessel walls reacted vigorously in all locations. Transferrin levels in rat brain were substantially higher than in rabbit brain. In the rabbit, maximum transferrin levels occurred in the cerebellum.(ABSTRACT TRUNCATED AT 250 WORDS)

Striatal dihydroxyphenylalanine decarboxylase and tyrosine hydroxylase protein in idiopathic Parkinson's disease and dominantly inherited olivopontocerebellar atrophy

We measured the levels of dopamine, tyrosine hydroxylase (TH) protein, and dihydroxyphenylalanine (DOPA) decarboxylase (DDC) protein in the striatum of 10 patients with idiopathic Parkinson's disease (PD) and 23 patients with dominantly inherited olivopontocerebellar atrophy (OPCA). The levels of dopamine were markedly reduced (2% of control) in the striatum of the patients with PD, whereas striatal dopamine in the patients with OPCA ranged from normal (> 60% of control) to moderately reduced (20-60% of control) to severely depleted (< 20% of control). Both TH and DDC protein levels were significantly lower than those of the controls in the striatum of all of the patients with PD and in the subgroup of patients with OPCA having severely depleted dopamine. In contradistinction, TH but not DDC protein levels were reduced in those patients with OPCA having moderately reduced dopamine levels. This suggests that in the early stage of nigrostriatal dopamine neurone degeneration, DDC levels may be less susceptible to neurodegenerative influences than is TH synthesis or, alternatively, DDC synthesis may be more aggressively upregulated. Unexpectedly, from the blot immunolabeling analysis an additional DDC-immunoreactive band of slightly lower apparent molecular mass was detected in two of the patients with PD and in 12 of the patients with OPCA. This additional DDC band, which was not present in any of the control subjects, may reflect posttranslational modification(s) of DDC related to the neurodegenerative process.

The cellular localization of malonyl-coenzyme A decarboxylase in rat brain

Malonyl-coenzyme A (CoA) decarboxylase (E.C.4.1.1.9) activity in brain is low but steadily increases after birth. The main physiological role of this mitochondrial enzyme is thought to be the stabilization of malonyl-CoA levels which change very little with brain growth. In an effort to visualize malonyl-CoA decarboxylase by immunocytochemistry, and to determine its developmental changes, the enzyme was purified by an efficient small-scale procedure involving isolation of mitochondria, extraction at high ionic strength, isoelectric focusing, column chromatography, and preparative polyacrylamide gel electrophoresis. The enzyme from brain showed the same apparent molecular weight (160 kDa) and was immunoreactive with antisera raised against malonyl-CoA decarboxylase from liver. Immunocytochemistry revealed early and extensive labeling of hepatocytes in rat liver but only delayed visualization in the brain. Most nerve cells of the cerebral cortex and many microglia were stained but the neurons of the cerebellar cortex did not become reactive. Golgi epithelial cells and their processes, the Bergmann glia, also showed reaction product.

The pathogenesis of superficial siderosis of the central nervous system

In advanced cases of superficial siderosis of the human central nervous system, the clinical triad of hearing loss, cerebellar ataxia, and myelopathy permits the diagnosis at the bedside, and magnetic resonance imaging readily confirms the hemosiderin deposits in brainstem, cerebellum, and spinal cord. To study the pathogenesis of this condition and explain the selective vulnerability of the cerebellum, experimental siderosis was induced in rabbits by the repeated intracisternal injection of autologous red blood cells. The earliest cellular response in the cerebellar molecular layer was hyperplasia and hypertrophy of microglia as displayed by immunocytochemistry for ferritin. Microglia also contained iron, but ferritin biosynthesis appeared to proceed without commensurate iron accumulation. This early apoferritin response probably occurred due to the presence of heme, rather than iron, in the cerebrospinal fluid and subpial tissue. Ferritin biosynthesis is accelerated when the ferritin repressor protein is dissociated from ferritin messenger ribonucleic acid. A specific antiserum localized ferritin repressor protein predominantly to astrocytes including Bergmann glia. It is proposed that abundance and proximity of ferritin repressor protein--immunoreactive Bergmann glia and ferritin-containing microglia in the cerebellar molecular layer permit prompt cellular interaction in the conversion of heme to ferritin and ultimately hemosiderin.

Immunocytochemical studies on the vimentin distribution and cell proliferation of fibroblasts in patients with Friedreich's ataxia

Fibroblasts obtained from patients with Friedreich's ataxia and normal control subjects were studied by immunocytochemistry for intermediate filament vimentin and also for in vitro proliferation. Trypsinized cells were seeded on coverslips and incubated for 1.5 h and 24 h. The expression of vimentin in cells was investigated by immunofluorescence microscopy. Cell proliferation was studied with BrdU antibody technique. Cells from patients with Friedreich's ataxia showed a slower outgrowth of vimentin filaments in comparison to cells from normal controls. These cells also incorporated less 5-bromo-2'-deoxyuridine (BrdU) into their DNA. The observations may be relevant to the clinical manifestations of the disease which involves many organs in addition to brain and spinal cord.

Experimental superficial siderosis of the central nervous system: biochemical correlates

The pathogenesis of superficial siderosis of the central nervous system (CNS) may be examined by the repeated intracisternal injection of washed autologous red blood cells (RBC). In rabbits, the injections cause the accumulation of iron in the cytoplasm of microglial cells and astrocytes of cerebellar and cerebral cortices. Immunocytochemistry for ferritin reveals enhanced reaction product mainly in microglia but hemosiderin occurs only after extending the injections to 6 months. In an effort to determine the biochemical correlates of these morphological changes, iron, ferritin, ferritin subunits and the ferritin repressor protein (FRP) were quantitated. There was no increase of total iron or ferritin in the exposed cortical areas. However, the injections of RBC caused dramatic shifts of the relative contributions by heavy (H-) and light (L-) ferritin subunits. The initial response was a prompt increase of the H/L ratio to over 4.0 from the normal ratio near 1.0. Extended injections caused the ratio to drop to below unity, and the predominance of L-ferritin at 6 months coincided with the appearance of granular hemosiderin. This investigation also confirmed the presence of FRP in rabbit brain cytosols but the induction of experimental superficial siderosis did not change its levels or in vitro affinity for the iron-responsive element in ferritin messenger ribonucleic acid. It is proposed that the incrustation by hemosiderin which characterizes superficial siderosis of the CNS in humans occurs when prolonged exposure to hemoglobin produces persistent shifts of the H/L-ratios by accumulation of L-ferritin.

Myelin deficiency in female rats due to a mutation in the PLP gene

Myelin deficiency (md) in female rats due to a mutation in the X-linked proteolipid protein (PLP) gene is caused by X-chromosome monosomy. Cytogenetic analysis revealed a single X karyotype [41,X(md/0)]. An immunocytochemical, electron microscopic, and biochemical study was performed on male and female md rats. The central nervous system (CNS) of the female md rat [41,X(md/0)] revealed the same total lack of PLP as the CNS of the affected male littermate [42,XY(md/Y)]. Immunocytochemistry for myelin basic protein (MBP), myelin-associated glycoprotein (MAG), and 2',3'-cyclic nucleotide-3'-phosphodiesterase (CNP) revealed "islands" of myelin sheath-like reaction product in both. Electron microscopy showed great paucity of compact myelin sheaths in 41,X(md/0) and 42,XY(md/Y). Reduced levels of MPB, MAG, and CNP were confirmed for both sexes but MAG and CNP were substantially higher in 41,X(md/0). Sexual differentiation of the brain may account for the observed differences since normal female reproductive organs are present in the md female rat.

Experimental superficial siderosis of the central nervous system. I. Morphological observations

Autologous washed red blood cells were injected weekly over a period of three to six months into the cisterna magna of adult New Zealand white rabbits. After three months, the surface of the brain stem, cerebellum, and piriform cortex showed a distinct brown color, and staining of the gross specimens for iron produced an intense blue color which extended for a distance of 1-2 mm into the brain parenchyma. Enhanced iron stains of vibratome sections revealed the accumulation of reaction product in microglia and Bergmann glia of the cerebellar cortex, and in microglia and astrocytes of the piriform cortex. Ferritin immunocytochemistry revealed reaction product in cerebellar microglia and Bergmann glia which strongly resembled that obtained by the enhanced iron stain. In the piriform cortex, only microglia were reactive with anti-ferritin. Electron microscopy confirmed the accumulation of electron-dense ferritin granules only in the cytoplasm of microglia. Bergmann glia in the cerebellum and astrocytic processes in the piriform cortex were replete with intermediate filaments and contained an excess of glycogen. After six months, small granules of hemosiderin began to appear in cerebellar and piriform cortices. The observations support that the sequence of conversion of hemoglobin to ferritin and hemosiderin occurs in brain as in other organs.

The Purkinje cell and its afferents in human hereditary ataxia

The cerebellar cortex in patients with autosomal dominant and recessive ataxia was studied by Golgi impregnation and immunocytochemistry in order to gain further insight into the pathogenesis of neuronal atrophy which accompanies these disorders. Monoclonal antisera were used to visualize phosphorylated and non-phosphorylated neurofilament proteins, and a synapse-specific protein (P38; synaptophysin). Golgi stain and immunocytochemistry for non-phosphorylated neurofilament protein revealed partial or complete loss of distal Purkinje cell dendrities in the dominant cases and in one recessive case. Many preserved parallel fibres were shown by the monoclonal antibody to phosphorylated neurofilament protein. This antibody also gave strong reaction product in torpedoes. Axosomatic and axodendritic terminals on Purkinje cells were reduced in number, and loss of mossy fiber terminals was revealed by monoclonal anti-P38. The described methods provided additional morphological evidence of the heterogeneity of the hereditary ataxias. Purkinje cell atrophy progressed from loss and simplification of the dendritic tree to disappearance of the cell body. While these cells appeared to be especially vulnerable, other neurons of the molecular and granular layers were not exempt. There was evidence that at least some extracerebellar afferents, such as mossy fibers, were also affected by the disease process.

The origin of free brain malonate

Rat brain contains substantial concentrations of free malonate (192 nmol/g wet weight) but origin and biological importance of the dicarboxylic acid are poorly understood. A dietary source has been excluded. A recently described malonyl-CoA decarboxylase deficiency is associated with malonic aciduria and clinical manifestations, including mental retardation. In an effort to study the metabolic origin of free malonate, several labeled acetyl-CoA precursors were administered by intracerebral injection. [2-14C]pyruvate or [1,5-14C]citrate produced radioactive glutamate but failed to label malonate. In contrast, [1-14C]acetate, [2-14C]acetate, and [1-14C]butyrate were converted to labeled glutamate and malonate after the same route of administration. The intracerebral injection of [1-14C]-beta-alanine as a precursor of malonic semialdehyde and possibly free malonate did not give rise to radioactivity in the dicarboxylate. The labeling pattern of malonic acid is compatible with the reaction sequence: acetyl-CoA----malonyl-CoA----malonate. The final step is thought to occur by transfer of the CoA-group from malonyl-CoA to succinate and/or acetoacetate. Labeling of malonate from acetate is most effective at the age of 7 days when the net concentration of the dicarboxylic acid in rat brain is still very low. At this age, butyrate was a better precursor of malonate than acetate. It is proposed that fatty acid oxidation provides the acetyl-CoA which functions as the precursor of free brain malonate. Compartmentation of malonate biosynthesis is likely because the acetyl-CoA precursors citrate and pyruvate are ineffective.

Familial amyloid polyneuropathy: alanine-for-threonine substitution in the transthyretin (prealbumin) molecule

A previously reported family with amyloid polyneuropathy (FAP) was reinvestigated to determine the type of mutation in the transthyretin (prealbumin) molecule. Transthyretin was isolated from amyloid-laden myocardium and serum, and tryptic peptides were resolved by high-performance liquid chromatography. Amino acid sequencing of an anomalous peptide revealed an alanine-for-threonine substitution corresponding to position No. 60 of the transthyretin monomer. Detection of the FAP gene in asymptomatic carriers was accomplished by hybrid isoelectric focusing of transthyretin in the presence of dithiothreitol and high concentrations of urea, and by Southern blotting of Pvull-digested leukocyte deoxyribonucleic acid. This type of FAP was found to be identical to the previously described Appalachian amyloid. Patients with FAP and their asymptomatic gene-carrying offspring had significantly reduced levels of serum transthyretin and retinol-binding protein.

The nucleus pontis centralis caudalis in Huntington's disease

Slow saccadic eye movements occur in some patients with Huntington's disease (HD), and minor defects of supranuclear eye movement control can be demonstrated in the majority by neuroophthalmological laboratory methods. In the pathogenesis of slowed saccades, a lesion of the paramedian pontine reticular formation and specifically the nucleus pontis centralis caudalis was considered likely due to similar eye movement disturbances in well documented degenerative and vascular lesions of the lower pontine tegmentum. A systematic morphometric study was performed on the nucleus pontis centralis caudalis in 9 patients with HD. Two of them had grossly defective saccades during life, and 7 had normal eye movements on routine examination. In 8 patients, the nucleus was reduced in size, revealed a higher than normal neuronal density, and a striking loss of large neurons. One patient with HD and normal morphometric results had died 2 years after the onset of chorea from an unrelated illness. It is proposed that the nucleus pontis centralis caudalis is regularly affected in HD and that progressive loss of large neurons is the cause of saccadic slowing.

Familial oculoleptomeningeal amyloidosis. Report of a new family with unusual features

A family had a dominantly inherited amyloid angiopathy that involved the meninges of the brain and spinal cord, retina, vitreous humor, peripheral nerves, and systemic organs. Clinical features included hemiplegic migraine, periodic obtundation, psychosis, seizures, intracerebral hemorrhage, myelopathy, visual impairment, deafness, and peripheral neuropathy. Pathological findings consisted of amyloid deposition in the leptomeningeal and retinal vessels, in the vitreous humor, and in perivascular tissue throughout the body. Evaluation of the amyloid showed it to be a transthyretin (prealbumin). A brief course of plasmapheresis produced a short-lived decrease concentration in circulating transthyretin.

Brain hemosiderin and superficial siderosis of the central nervous system

Brain tissue from five patients with superficial siderosis of the central nervous system was examined by immunocytochemistry for ferritin, glial fibrillary acidic protein (GFAP), alpha 1-antitrypsin, and alpha 1-antichymotrypsin, and by lectin affinity cytochemistry with biotinylated Ricinus communis agglutinin-1 (RCA-1). The sections were pretreated with 2,2'-dipyridyl and sodium hydrosulfite to remove iron and to reveal the antigenic sites. In siderotic cerebellar cortex, ferritin reaction product occurred in the hemosiderin matrix, the cell bodies and processes of Bergmann glia, and in microglia. Astrocytes other than Bergmann glia did not contain ferritin reaction product. RCA-1 stained microglia and hemosiderin whereas antisera to alpha 1-antitrypsin and alpha 1-antichymotrypsin only reacted with iron-depleted granules. The selective vulnerability of the eighth cranial nerve was explained by the presence of ferritin-reactive and lectin-positive microglia. Hemosiderin isolated from frozen cerebellum contained ferritin, GFAP, and vimentin. The presence of the intermediate filament proteins was likely due to co-localization with hemosiderin granules in Bergmann glia. The ability of the brain to biosynthesize ferritin in response to prolonged contact with hemoglobin iron is thought to be the most important factor in the pathogenesis of superficial siderosis. The great severity of the lesion in the exposed cerebellar cortex is readily explained by accelerated ferritin biosynthesis in Bergmann glia.

Comparative immunocytochemistry of Pelizaeus-Merzbacher disease, the jimpy mouse, and the myelin-deficient rat

Patients with Pelizaeus-Merzbacher disease (PM), hemizygous mice with the jimpy mutation (jp/Y), and hemizygous rats with X-linked myelin deficiency (md/Y) share a profound lack of proteolipid protein (PLP) in their central nervous systems (CNS). The peripheral nervous system is normal. These X-linked disorders are associated with or actually caused by the lack of normal oligodendrocytes. Vibratome sections of brain were incubated with antisera to myelin basic protein (MBP), myelin-associated glycoprotein (MAG), 2':3'-cyclic-nucleotide 3'-phosphodiesterase (CNP) (EC 3.1.4.37), PLP, a synthetic PLP-peptide, glial fibrillary acidic protein (GFAP), and transferrin. Reaction product was developed by sequential incubation with biotinylated second antibodies, the avidin-biotin-peroxidase complex (ABC), and diaminobenzidine (DAB) plus hydrogen peroxide as chromogenic substrates. In PM, jp/Y and md/Y, islands of myelin-like structures were revealed by antisera to MBP, MAG, and CNP. Reaction product after application of anti-PLP was absent. Reaction product after anti-PLP-peptide was restricted to infrequent bizarre cells possibly representing abnormal oligodendroglia. The lack of oligodendrocytes in jp/Y and md/Y could also be confirmed by immunocytochemistry for transferrin.

Amyloid fibril protein in familial amyloidosis with cranial neuropathy and corneal lattice dystrophy (FAP type IV) is related to transthyretin

Immunocytochemical methods were used to study the nature of the amyloid deposits in the Finnish type-familial amyloid polyneuropathy (FAP) type IV, which is characterized by cranial neuropathy and corneal lattice dystrophy. Commercial antisera to human plasma transthyretin (prealbumin) did not stain the amyloid deposits, but in every case a positive staining was obtained with antibodies raised against transthyretin-related amyloid fibril whole protein isolated from the myocardium of a patient with familial amyloid polyneuropathy from the state of New York. The FAP type IV amyloid deposits stained also with antiserum to serum amyloid P component, but did not stain with antisera to retinol-binding protein, amyloid A protein, gamma-trace protein, beta 2-microglobulin, or immunoglobulin light chains. The serum level of serum transthyretin was significantly decreased in FAP type IV patients (256 +/- 75 (SD) mg/L, n = 15) as compared with Finnish control subjects (360 +/- 56 mg/L, n = 30, P less than 0.001), whereas the level of retinol-binding protein was within the normal range. The results of this study strongly suggest that the amyloid fibril protein in FAP type IV amyloidosis is related to transthyretin.

Effect of free malonate on the utilization of glutamate by rat brain mitochondria

Malonate is an effective inhibitor of succinate dehydrogenase in preparations from brain and other organs. This property was reexamined in isolated rat brain mitochondria during incubation with L-glutamate. The biosynthesis of aspartate was determined by a standard spectrofluorometric method and a radiometric technique. The latter was suitable for aspartate assay after very brief incubations of mitochondria with glutamate. At a concentration of 1 mM or higher, malonate totally inhibited aspartate biosynthesis. At 0.2 mM, the inhibitory effect was still present. It is thus possible that the natural concentration of free malonate in adult rat brain of 192 nmol/g wet weight exerts an effect on citric acid cycle reactions in vivo. The inhibition of glutamate utilization by malonate was readily overcome by the addition of malate which provided oxaloacetate for the transamination of glutamate. The reaction was accompanied by the accumulation of 2-oxoglutarate. The metabolism of glutamate was also blocked by inclusion of arsenite and gamma-vinyl-gamma-aminobutyric acid but again added malate allowed transamination to resume. When arsenite and gamma-vinyl-gamma-aminobutyric acid were present, the role of malonate as an inhibitor of malate entry into the mitochondrial interior could be determined without considering the inhibition of succinate dehydrogenase. The apparent Km and Vmax values for uninhibited malate entry were 0.01 mM and 100 nmol/mg protein/min, respectively. Malonate was a competitive inhibitor of malate transport (Ki = 0.75 mM).

Defective biosynthesis of proteolipid protein in Pelizaeus-Merzbacher disease

The brain of an 18-year-old patient with Pelizaeus-Merzbacher disease was examined by standard neuropathological and biochemical methods and by immunocytochemical and immunochemical techniques. Analysis revealed a lack of myelin-specific lipids, but showed a residual immunoreactivity for myelin basic protein, myelin-associated glycoprotein, and 2',3'-cyclic nucleotide-3'-phosphodiesterase. Examination by immunocytochemistry and enzyme-linked immunosorbent assay showed an absence of proteolipid apoprotein (lipophilin). The peripheral nervous system was normal. Pelizaeus-Merzbacher disease in humans shares many neuropathological and biochemical features with X-linked mutations in animals, e.g., the jimpy mouse and myelin-deficient rat. The specificity of this protein deficiency in Pelizaeus-Merzbacher disease gains additional support from the recent mapping of the lipophilin gene to the human X chromosome.

Olivopontocerebellar atrophy: immunocytochemical and Golgi observations

Brain tissue was obtained promptly after death from a patient with autosomal dominant olivopontocerebellar atrophy and studied by immunocytochemistry and a Golgi technique. Antiglutamic acid decarboxylase showed severe loss of Purkinje cells and their terminals in the dentate nucleus. Stains for neuron-specific enolase (NSE) and microtubule-associated proteins (MAP) confirmed the integrity of the dentate nucleus. Basket and stellate cells revealed secondary changes, but Golgi neurons were intact. Methods for NSE and MAP disclosed dendritic alterations and loss of neurons in the basis pontis and inferior olivary nuclei. Golgi impregnation of Purkinje cells showed loss of major dendrites, paucity of spiny branchlets, and axonal expansions.

Familial amyloid polyneuropathy

Amyloid fibrils were isolated from the myocardium of two patients with familial amyloid polyneuropathy. The solubilized amyloid fibril whole protein shared immunologic determinants with normal human serum prealbumin (transthyretin), but revealed subtle differences on immunoelectrophoresis and radial immunodiffusion. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis, amyloid fibril whole protein was resolved into numerous bands that reacted with antitransthyretin on immunoblots. The whole protein also contained peptide fragments of fibronectin, but was devoid of amyloid P protein. An antiserum raised against the whole protein was suitable for immunocytochemistry of amyloid in paraffin sections. In contrast, commercial antitransthyretin, raised against the intact tetrameric protein failed to react with tissue amyloid. Immunochemical and immunocytochemical results support the concept that familial amyloid polyneuropathy with cardiomyopathy is due to infiltration of susceptible tissues by an anomalous transthyretin.

Malonate, malonyl-coenzyme A, and acetyl-coenzyme A in developing rat brain

Free malonate, malonyl-coenzyme A (malonyl-CoA), and acetyl-CoA were assayed in rat brain at developmental ages from the 20th day of gestation to 60 days of postnatal life. The determination of malonate was based on its conversion to malonyl-CoA and decarboxylation to acetyl-CoA by enzyme extracts from Pseudomonas fluorescens. The resulting acetyl-CoA reacted with [4-14C]oxaloacetate to form [5-14C]citrate, which was isolated by TLC. Malonyl-CoA in perchloric acid extracts from brain was converted to acetyl-CoA by rat liver mitochondrial malonyl-CoA decarboxylase (EC 4.1.1.9). Acetyl-CoA derived from this step was assayed by a modified CoA-cycling procedure. Brain acetyl-CoA was also assayed by CoA cycling. Prenatal brain contained no free malonate but malonyl-CoA was present. The acetyl-CoA level was relatively high just prior to birth and declined slightly with growth. Malonate concentrations after birth rose rapidly to reach 192 nmol/g wet weight at 60 days. Adult levels for malonyl-CoA and acetyl-CoA were 1.83 and 1.90 nmol/g wet weight, respectively. The origin and natural role of free malonate in brain are not known but deacylation of malonyl-CoA by reversal of the malonyl-CoA synthetase reaction is postulated. Rat liver and kidney also contain substantial concentrations of free malonate.

Fine structure of neurons of the hypertrophied human inferior olive

Ultrastructural study of hypertrophied inferior olives from three cases of palatal myoclonus revealed tha nerve cells not infrequently contained numerous round, homogeneously electron-dense granules (mean diameter, 360 nm) located within expanded cisternal profiles of rough endoplasmic reticulum (RER). Control tissue did not contain similar structures. These granules may consist of proteinaceous secretion of the RER which, for reason unknown, accumulates during transsynaptic degeneration of the inferior olive. Additional noteworthy electron microscopic features of neurons of the hypertrophied olive were as follows: 1. neurofilamentous hyperplasia, greater in dendrites than in perikarya; 2. vacuoles in intermediate and large (up to 15 mum) size, derived from RER; and 3. prominent intracytoplasmic protrusions by boutons containing dense core vesicles (mean diameter, 98 nm). Glomeruloids were identified ultrastructurally and consisted of numerous boutons interspersed among neurofilament-rich dendrites and occasional, filament-packed astrocytic profiles. Frequently, these boutons also contained dense-core vesicles. It seems possible that the boutons mentioned may arise from collateral axonal sprouts.

Central nervous system vasculitis in cytomegalovirus infection

A 51-year-old man received cyclophosphamide, vincristine, procarbazine and prednisone in the treatment of a small-cell undifferentiated lymphoma. Two years later, he developed a rapidly progressive neurological syndrome characterized by a decline in alertness, deafness, blindness and paraplegia. Examination of his eyes revealed severe hemorrhagic chorioretinitis. Leg weakness was thought to be due to transverse myelopathy at a thoracic level. He had a grand mal convulsion and died from terminal bronchopneumonia. Autopsy examination of the eyes revealed sweeping destruction of the retina due to inclusion body chorioretinitis. The brain and spinal cord showed multiple small infarcts accounting for the deafness and paraplegia. The lesions were due to occlusive arteritis in gray and white matter. Veins were also involved. Tissue surrounding the foci of necrosis contained cells with intranuclear an intracytoplasmic inclusion bodies. Some of the Cowdry type A inclusion bodies were large, measuring 30 micrometer in diameter and were located in enlarged cells. Electron microscopy of retina and brain tissue disclosed virus particles compatible with cytomegalovirus. The subject of cerebral and ocular angiitis due to herpes virus infections is reviewed.

Oligodendroglioma of the medulla oblongata in a neonate

A 4-month-old boy had recurrent attacks of apnea before progressive quadriparesis, ocular motility disturbance, and depressed corneal reflexes led to the discovery of a posterior fossa mass. Death occurred postoperatively during prolonged apnea. Necropsy disclosed an oligodendroglioma of the medulla oblongata. A review of this rare neoplasm in the neonatal period is given.

Hereditary ataxia and the sixth chromosome

Possible linkage of the gene or genes for dominant hereditary ataxia and three genetic markers on the short arm of the sixth chromosome (HLA, properdin factor B [Bf], and glyoxalase I) was investigated in five families. Logarithmic odds (lod scores) were calculated for the linkages and found to be either inconclusive or in favor of nonlinkage. Caution is advised in the summing of lod scores for separate families because of the wide spectrum of clinical and anatomical manifestations of dominant hereditary ataxia. Three families with recessive hereditary ataxia were also studied. Identical haplotypes occurred in affected and unaffected siblings. It did not appear likely that the recessive genes of the parents were transmitted in linkage with the markers on the short arm of the sixth chromosome.

Olivary hypertrophy: histochemical demonstration of hydrolytic enzymes

Of four patients with palatal myoclonus, three had infarcts resulting from atherosclerosis, and one had cerebral emboli from a left atrial myxoma. Three specimens showed lesions in the brainstem and bilateral hypertrophy of the inferior olivary nuclei; the fourth revealed unilateral olivary changes caused by an infarct in the contralateral dentate nucleus. After incubation for acetylcholinesterase, neuropilar and capillary wall staining were absent or much reduced, but there was increased denisty of reaction product in the neuronal cell bodies and in numerous tortuous dendrites. Methods for acid phosphatase showed strong activity in the dendrites and glomeruloid structures of the diseased olives. Reactions for nonspecific esterase indicated dendritic expansion and reduced staining density in nerve cell bodies, but augmented glial reactivity.

Huntington's chorea. Its impact on the spouse

Huntington's chorea imposes a direct imprint on the life of the spouse of the affected patient. Interviews with 15 wives of patients with Huntington's chorea revealed that none of them knew prior to marriage of the presence of a heritable disease within the husband's family. When informed of the diagnosis, the wife reacted with disbelief and denial. As she became aware of the steady progression of the disease and the threat of transmission to her children, her response changed to resentment and hostility. The disease permeated the entire life of the unaffected spouse: her life style, family responsibility, goals, and marital relationship. In essence, the wife became inextricably involved in the disease and suffered continuous trauma from it.

Fatty acid biosynthesis in Wallerian degeneration of rat sciatic nerve

In-vitro fatty acid biosynthesis was studied in normal rat sciatic nerve and during wallerian degeneration. Normal nerve incorporated 1,3-C14-malonyl-CoA and 1-C14-acetyl-CoA into fatty acids by a de-novo biosynthetic pathway. The reaction product with highest radioactivity was palmitic acid, and the free fatty acids of nerve contained 90% of the total fatty acid label. During wallerian degeneration, there was a rapid increase of fatty acid biosynthesis that reached a peak between 16 and 24 days after nerve section. Values declined to normal levels at approximately 50 days.

Marchiafava-Bignami disease

Marchiafava-Bignami disease was diagnosed postmortem in a 39-year-old man who drank excessive amounts of white port wine. This is the fifth report of the disease in a native North-American with no Italian ancestry. The lesion involved the corpus callosum and hippocampal commissure but spared the anterior commissure, middle cerebellar peduncles, optic chiasm, and centrum semiovale. Wernicke-Korsakoff encephalopathy and pellagroid neuronal changes were also present.

Atypical progressive multifocal leukoencephalopathy and primary cerebral malignant lymphoma

Atypical progressive multifocal leukoencephalopathy occurred in an 82-year-old man with long-standing chronic lymphocytic leukemia. The multifocal white matter lesions revealed demyelination and gliosis, relative preservation of axons and a prominent plasma cell infiltrate. Bizarre astrocytes were uncommon. There were no changes in the oligodendroglial nuclei and no inclusion bodies. Electron and immunohistofluorescence microscopy for papova virus were negative. In addition to this leukoencephalopathy a small primary cerebral lymphoma was present in the right occipital lobe. The tumor cells were plasmacytoid in appearance and their cytoplasm stained well with pyronin. They contained IgG by immunohistofluorescence microscopy. The neoplasm was considered an immunoblastic sarcoma (reticulum cell sarcoma) and thought to arise directly within foci of demyelination. Both disease processes, leukoencephalopathy and lymphoma, may have occurred on a background of immunosuppression.

Adult-onset hereditary ataxia in Scotland

A systematic search for cases of adult-onset hereditary ataxia was conducted on location in Scotland. The investigation resulted in the discovery of eight pedigrees with 42 patients of whom 16 were alive in 1975. Nine patients were examined by the authors and recent hospital records were available on the remaining seven. The clinical features were quite variable. In declining order of frequency, findings were gait and limb ataxia, dysarthria, hyperreflexia, extrapyramidal motor disturbances, impaired vibratory sense, spasticity, defects of extraocular movements and nystagmus, reflex depression, Babinski signs, impaired joint position sense, muscle weakness, optic atrophy, and mental abnormalities. Foot deformity occurred only once. Inheritance was compatible with autosomal dominant transmission, but complicated by consanguinity in two families. The minimum prevalence was calculated as 0.31/100,000. Autopsy in two members in one family revealed olivopontocerebellar degeneration.

Supranuclear ophthalmoplegia in olivopontocerebellar degeneration

Autosomal dominant olivopontocerebellar degeneration was diagnosed in a family of Scottish ancestry by clinical examination and autopsy. In addition to having progressive cerebellar ataxia, head titubation, and severe dysarthria, the patients are unable to initiate saccadic eye movements. Slow pursuit movements are normal. Reflex movements of the eyes caused by passive rotation or caloric labyrinthine stimulation are not impaired but are not associated with nystagmus. The phenomenon can be classified as supranuclear pseudo-ophthalmoplegia. It differs from congenital ocular motor apraxia in age at onset and the absence of random eye movements. The anatomic lesion responsible for the defect of saccadic eye movements remains to be established.